Immunohistochemistry (IHC) analysis with MVD calculations will be assessed and correlated to the imaging findings. Paired biopsies of tumors and normal GI mucosa obtained during endoscopic procedures (ensuring co-registration with M-NBI and pCLE examined regions) will be processed for fixation in 10% neutral buffered formalin (NBF), paraffin embedding and sectioning. For MVD analysis, the blocks will be completely cut in serial sections 4-25 μm-thick, with one thick section for every 10 thin sections. In order to assess the total vascular architecture we will utilize non-selective endothelial cell markers, such as anti-CD31 and anti-CD34 antibodies.